This invention relates to manually operated devices for treating the surface of a work object and, more particularly, is directed to devices of this nature intended to sand, polish, wax, or the like such surfaces.
An age-old method of sanding or otherwise treating a work surface has been to take the material with which the surface is to be treated and manually hold it to a block of wood or the like. Thus, with particular reference to sanding, the sandpaper is generally wrapped over a block of wood of a desired configuration. The user grasps the sandpaper and the block with his hand. Usually, the combination is found to be useful, but clumsy. This age-old method requires the retaining of the block of wood. Furthermore, and more importantly, it is desirable to have a sanding or other work surfaces treating device which is, at once, disposable and efficient in use. An essential characteristic of such a device must be that the material used to treat the work surface is substantially continuous and relatively unyielding so that the manual application of force will be evenly applied to the work surface.
There have been a number of attempts to accomplish the dual goals of providing a sandpapering or other work surface treating device which is, at once, efficient in use and, by the nature of its construction, disposable. The previous devices have had, however, certain disadvantages. Thus, for example, Smith, in U.S. Pat. No. 1,146,359, provides for a trifoliate structure, made of three separate leaves of sandpaper, each secured to one another. Each sheet of sandpaper is divided in half, with one half of a sheet of sandpaper secured to the other half of a second sheet of sandpaper. The remaining halves of the first and second sheets of sandpaper are, in turn, secured to a third sheet of sandpaper. Each trifoliate sandpaper sheet has an exposed sanding surface. Smith teaches that this structure is substantially rectangular, "Y" or "T" shaped in cross section, and folded along the length thereof.
Kaufman, in U.S. Pat. No. 2,414,535, attempts another approach. Kaufman teaches a sheet of sandpaper secured to a rigid backing sheet made of cloth or paper. The device is substantially rectangular and perforated along parallel lines. Kaufman teaches that a handle may be formed by folding up the marginal parallel strips of the backing, thereby leaving exposed the sandpaper sheet on either side and a portion of the sandpaper secured to the backing sheet between the marginal strips.
Still another example is provided by Norris III, in U.S. Pat. No. 3,623,282. There, Norris III forms a triangularly shaped member which is grasped between the thumb and forefinger by the user. Each sheet which makes up the member is flexible. The pyramidal structure is so flexible that it can only be conveniently used within the tiny confines described by the distance between the thumb and forefinger of the user. Any larger area provides a wholly flexible, non-rigid surface which distributes forces unequally to the work surface.
Each of these aforementioned devices, in its own way, presents significant disadvantages. The sanding surface suggested by Smith is discontinuous, separated and weakened by a fold line. Further, the user is required to grasp treatment surfaces (e.g. sandpaper), making such use uncomfortable, at the very least. The device proposed by Kaufman leaves the marginally exposed sandpapering sheet, amounting in many cases to almost 2/3 of the area of sandpaper, unsupported by the backing sheet, thereby forming a very inefficient device. Further, the handle formed by the marginal strips of backing sheet requires support by either an index finger or block of wood disposed between. It should be noted that it is the obvious goal of any disposable sanding device to avoid the use of added tools, such as a strip of wood, in order to make the sanding device workable. Thus, there is little difference between the device of Kaufman and the age-old combination of sandpaper and a block of wood. In the device proposed by Norris III, the effective area use is only in the relatively small area described between the thumb and forefinger of the person holding the device. Furthermore, because the pyramidal structure is a three-sided, triangular, flexible sheet, very little useful rigid pressure can be brought against the surface of the work object.